The postal service has directed considerable resources to improving the sorting and delivery of letters and related postal matters. Automated scanners sort mail by zip code and automatic equipment is available for transporting the mail within the separate postal stations. As part of this concept the postal service employs a system in which mail, such as letters addressed to a single destination (e.g., one zip code), is placed in a marked tray. In order to prevent loss of the individual letters, or the introduction of letters for an alternate destination, the tray is inserted into an open-ended sleeve. Thus, the tray in the sleeve is easily transported. The insertion of the tray into the sleeve is presently being performed manually which is inefficient, slow and labor intensive and is a portion of the overall mail handling approach which is urgently in need of improvement.
An apparatus for inserting articles into open-ended receptacles is disclosed in U.S. Pat. No. 1,407,581 issued to Rose Feb. 21, 1922. Outer members are fed into the apparatus in a collapsed condition by a pair of arm-like pushers and opened by a wedge-shaped member. A reciprocatable slider thrusts the inner member into the outer member. U.S. Pat. No. 3,299,610 issued to Webster Jan. 24, 1967 discloses an apparatus for filling sleeve packages wherein a carton or sleeve is erected at the sleeving station with an open end thereof directed along the path of a package which is moving along a predetermined path toward the sleeving station. The carton or sleeve is held stationary by suction applied to the underside of the sleeve while the package is pushed into the open end of the carton or sleeve. U.S. Pat. No. 4,012,887 issued to Calvert Mar. 22, 1977 discloses a packaging machine which withdraws collapsed sleeve-type containers from a hopper by suction means applied to the bottom of the sleeve and sets up the sleeve to receive bottles through the open end. End flaps are closed on the sleeve. U.S. Pat. No. 4,693,055 issued to Olsen, Jr. et al Sep. 15, 1987 disclose a machine for feeding beverage cans to open-ended carrier sleeves. U.S. Pat. No. 4,869,052 issued to Calvert Sep. 26, 1989 discloses a packaging machine. Collapsed sleeve-type articles are withdrawn in sequence from a hopper by suction cup means which then holds each carton at a loading station while a plurality of articles are inserted through an open end of each container. Flaps for the open ends of the container are then closed.
Although the packaging machines are useful for the purposes for which they were designed, a simpler, more efficient sleeving machine is needed for the postal service requirements.